Corner joint for wooden frame



Nov. l0, 1964 w. scHLl-:GEL 3,156,022

CORNER JOINT FOR WOODEN FRAME Filed March 14, 1961 2 Sheets-Sheet 1 4 /M/E/vrofe;

WERNER SCHLEGEL Nov. l0, 1964 w. scHLEGEl.

CORNER JOINT FOR WOODEN FRAME 2 Sheets-Sheet 2 Filed March 14, 1961 /A/VE/vro/P www SCHLEGEL BY ,W MW

AGENT United States Patent O 3,156,022 CORNER JOINT FOR WOODEN FRAME Werner Schlegel, Kastanienallee 3, Essen, Germany Filed Mar. 14, 1961, Ser. No. 95,568 Claims priority, application Germany, Mar. 18, 1960, Sch 27,612 1 Claim. (Cl. Ztl-92) My present invention relates to wooden frames for windows, doors etc. and, more particularly, to a construction of a corner joint for such frames.

The tendency of wood to warp, swell and shrink in the course of time and with varying atmospheric conditions has always created difficulties in the maintenance of a desired (usually right) angle between two wooden frame members interconnected in a miter joint. Brackets, false corners and similar restraining devices have not, in the past, effectively prevented the deformation of wooden frames exposed to the iniluences of wind and weather.

The stresses arising in a miter joint are manifold and totally unpredictable; they depend in large measure upon the character of the wood, the degree of its seasoning and the direction of the cut, along with climatic conditions. Alternate swelling and shrinking of the wood with variations in ambient humidity, moreover, tend to weaken the bonding force of nails, screws or the like and to bring about progressive distortion through the development of cumulative stresses whose magnitude is usually underestimated and which cannot be overcome by the clamping action of conventional external reinforcements.

It is, therefore, the general object of my present invention to provide means for effectively strengthening a miter joint between wooden frame members and dependably maintaining the shape of such joint even in the face of severe atmospheric conditions.

A more particular object of this invention is to provide an improved joint for the corners of an exposed retaining frame serving as a support for a window assembly inserted in a building embrasure, eg. as disclosed in my cepending application Ser. No. 16,996 filed March 23, 196i), now Patent No. 3,018,524 issued January 30, 1962.

In order to realize the foregoing objects I provide, in accordance with my instant invention, a miter joint having imbedded therein one or more elements bridging the wooden frame members forming the joint, in combination with one or more fasteners anchored to these frame members for holding them in tight contact with each other and with the imbedded element or elements. Each fastener may be in the form of a countersunk screw extending transversely to the joint, the head and/or the nut of the screw preferably bearing upon one or more resilient washers designed to compensate dimensional changes perpendicular to the joint. The imbedded element or elements, which in contradistinction to the fasteners do not exert any clamping action, are designed to resist shear and other stresses effective in planes generally parallel to the joint, thus counteracting the complex and unpredictable forces which tend to disalign the jointed members. The imbedded element or elements may comprise, for example, a metal bolt with slotted and tapered extremities, respectively received in narrow conical recesses on opposite sides of the joint, or one or more substantially flat and generally circular springs of the dished-disk type inserted into suitable cavities. The space accommodating the imbedded element or elements should, in any event, be so narrowly dimensioned as to place same under a stress which eliminates any playin the direction of shear, i.e. a direction parallel to the beveled joint faces in which such element is expandable. The counters'unk'fasteners may be concealed from View by suitable masking inserts.

The above and other objects, features and advantages of my invention will become more fully apparent from the following detailed description, reference being made to the accompanying drawing in which:

FIG. 1 is a sectional elevational view of a window assembly, generally similar to that disclosed in my aboveidentified copending application, which includes a retaining frame embodying the present invention;

FIG. 2 is a horizontal sectional View of the structure shown in FIG. l;

FIG. 3 shows, partly in section, a corner of the retaining frame of FIGS. 1 and 2;

FIG. 4 is a sectional view taken on the line IV-IV of FIG. 3;

FIG. 4a is an end View of a shear-resisting element imbedded in the frame of FIGS. 3 and 4;

FIG. 5 is a view similar to FIG. 4, showing a construction with different shear-resisting elements;

FIG. 6 is a sectional view taken on the line VI--VI of FIG. 5; and

FIGS. 7 and 7a are respectively a cross-sectional view and a face view of a further modification of a shearresisting element adapted to be used in the construction of FIGS. 5 and 6.

The window construction shown in FIGS. 1 and 2 generally resembles that of my aforementioned copending application and includes, within a finished building embrasure 1 a window frame 2 carrying a sash 3 and supported by an external frame 4. The frame units 2, 3 and 4 are all made of wood; of these, the outerv frame 4 is located on the weather side of the building and is therefore particularly exposed to atmospheric conditions tending to deform it through warping, swelling and shrinkage. j

The retaining frame 4 has a shoulder 4a which bears, through the intermediary of a resilient gasket, preferably consisting of bitumen-impregnated foam resin, upon the outer wall of the embrasure. The inner frame 2 is received with all-around clearance within the window opening of the embrasure and is formed with an inwardly projecting rectangular ledge 11. The sash 3 carries one or more panes 26.

Into the clearance between frame 2 and embrasure 1 project a number of lugs 6 which are anchored to the building wall and are traversed by screws 7 engaging blocks 8 spaced around the periphery of the frame 2. The blocks 8 are rigid with the frame 4, e.g. by being secured thereto with the aid of screws 23 whereby the frame 4 is urged against the gasket 5 by the action of the screws 7. Similar screws 10 pass through wedges 9, which are rigid with frame 2, and through complementary wedges 9' which are movable relatively to the frame 2 and the embrasure 1 for the purpose of centering the former Within the latter as more fully described in my aboveidentified copending application. The screws 7 and 10 along with the blocks S and the wedges 9, 9' are concealed from View by a masking frame 12 removably mounted.

on the ledge 11. Reference will now be made to FIGS. 3, 4 and 4a for a description of the miter joint formed at each corner of the outer frame 4. The orthogonally adjoining members of this frame are beveled to form end faces 13 in the usual manner. They are, furthermore, provided with matching truste-conical bores 1S which are shown to be any dimensional changes of the bores 18 due to shrinkage or swelling will be compensated by the relative mobility of these sectors.

The frame members are held together by an elongated fastener in the form of a screw 14 which lies transversely to the plane of the end faces 13 at a location beyond the bores 18 and parallel to their axis. The head 14a of screw 14 and a nut 15 form opposite terminations which bear upon the respective members of frame 4 through the intermediary of a pair of resilient washers 16, the latter being held under sufficient tension to compensate for shrinkage of the Wood while conversely allowing for a certain swelling thereof. The head 14a and the nut 15 are received in respective external recesses 24, 25 of the frame 4 which are shown masked by inserts 21 and 22, respectively; insert 21 is a wooden block whereas insert 22 is a pressed metal cap whose upper edge (as viewed in FIG. 3) is interposed between the wall of recess 25 and the nut 15 to prevent rotation of the latter. It will be apparent that the bolt 14 may be locked in similar manner or may be given a non-circular cross-section so as to be secured against rotation. Other means known per se to prevent a loosening of the resilient clamping connection between screw 14 and nut 15 along with washers 16 may, of course, be employed.

In FIGS. 5 and 6 I have shown modified frame meinbers 4 formed with recesses 18 which together dene a cavity of generally elliptical cross-section bisected by the plane of end faces 13. Within that cavity, and bisected by the same plane, are a pair of dished-disk springs 19 positioned backtoback and held under sufficient resilient stress to compensate for changes in the volume of the cavity. The springs 19 may be slightly bent back at their edges for easier introduction into the recesses 18.

As illustrated in FIGS. 7 and 7a, the two disk springs 19 may also be replaced by a single such spring 20 of corrugated cross-section.

My invention is, of source, not limited to the specific embodiments described and illustrated but may be realized in various modifications Without departing from the spirit and scope of the appended claim.

I claim:

A frame structure comprising a pair of orthogonally adjoining wooden frame members provided with beveled end faces forming a miter joint, said members being formed at said end faces with respective recesses which are matchingly aligned with each other at said joint and progressively decrease in width in a direction generally perpendicular to said end faces, fastening means including a screw extending transversely to said end faces across said joint at a location beyond said recesses for holding said members together, said screw being provided with opposite terminations respectively bearing upon said members, a shear-resisting element with outwardly tapering halves resiliently expandable against the Walls of said recesses in a direction parallel to said end faces, said element being seated with close fit in said recesses and bridging said members, and at least one spring washer interposed between one of said terminations and the respective member for continuously urging said members toward each other, thereby wedging said element into said recesses.

References Cited in the file of this patent UNITED STATES PATENTS 58,627 Flagg Oct. 9, 1866 94,066 Betteley Aug. 24, 1869 1,057,813 Edler Apr. 1, 1913 1,287,678 Hall Dec. 17, 1918 1,786,497 Kriek Dec. 30, 1930 2,123,081 Sadenwater July 5, 1938 2,294,095 Pease Aug. 25, 1942 2,341,906 Cowbourne Feb. 15, 1944 2,858,584 Gaines Nov. 4, 1958 3,018,524 Schlegel Jan. 30, 1962 FOREIGN PATENTS 17,633 Great Britain Dec. 23, 1909 665,974 Great Britain Feb. 6, 1952 111,295 Switzerland Aug. 1, 1925 310,300 Switzerland Dec. 16, 1955 65,596 Sweden Nov. 22, 1926 

